Experimental evidence suggests that oxidative stress due to the accumulation of free radicals plays a role in the pathogenesis of cataracts and that the process can be prevented or ameliorated by antioxidants. In addition, a recent study found that cataract patients tended to have lower serum levels of vitamins C, E, or carotenoids than did control subjects. This investigation, which compared the self-reported consumption of supplementary vitamins by 175 cataract patients with that of 175 individually matched, cataract-free subjects, revealed that the latter group used significantly more supplementary vitamins C and E (p = 0.01 and 0.004, respectively). Inasmuch as the observed reduction in risk of cataracts was at least 50%, a randomized, controlled trial of vitamin supplementation in cataract prevention seems justified.